March 26, 2015
02:00 PM (EDT)

News Release Number: STScI-2015-10

Hubble and Chandra Discover Dark Matter Is Not as Sticky as Once Thought

March 26, 2015: In particle physics labs, like the Large Hadron Collider in Geneva, Switzerland,
scientists smash atoms together to study the underpinnings of matter and energy.
On the scale of the macrocosm, nature provides a similar experiment by crashing
clusters of galaxies together. Besides galaxies and gas, the galaxy clusters
contain huge amounts of dark matter. Dark matter is a transparent form of matter
that makes up most of the mass in the universe. During collisions, the clouds of
gas enveloping the galaxies crash into each other and slow down or stop.
Astronomers found that the dark matter continued straight through the violent
collisions, without slowing down relative to the galaxies. Their best explanation
is that the dark matter did not interact with visible particles, and it also
interacted less frequently with other dark matter than previously thought.
Astronomers used the Hubble Space Telescope and Chandra X-ray Observatory to study
72 large galaxy cluster collisions. Chandra traced the hot gas, and Hubble saw
how the invisible dark matter warps space and distorts the images of background
stars. This allowed for the distribution of dark matter in the collision to be
mapped. The finding narrows down the options for what this dark matter might be.

Join Hubble astronomers during the live Hubble Hangout at 3pm on Thurs.,
March 26, to learn even more about this study. Visit: http://hbbl.us/98X